By the present invention a unique vehicle undercarriage is offered which may be utilized for the transport of either merchandise supported directly upon its base or may be combined with a suitable superstructure such as a chair assembly for the transport of an individual. Maneuverability of the vehicle is significantly enhanced by the provision of extendable and retractable support assemblies which may be selectively actuated to achieve a variable wheelbase. The terrain or supporting surface is engaged at all times by an endless track, belt or tread on both sides of the vehicle which cooperate with unique take-up means automatically absorbing and letting out portions of the tread during variation of the effective vehicle wheelbase. Variations in the supporting terrain are readily accommodated by the present invention in view of novel variable pitch means included in the support assemblies and which are actuated to elevate or depress the distal portion of each end of the treads as elevated obstacles or depressions are encountered during the forward or rearward movement of the vehicle.
Alternative mechanisms are proposed for achieving variation of the effective length of the present vehicle wheelbase. In one aspect, fore and aft track drive assemblies are rectilinearly displaced between retracted and extended positions while another embodiment includes pivotally attached track assemblies displaceable about the distal portions of each track and swingable to alter the effective ground-engaging portion of the tracks. An important feature to realize is that in all of the variable positions of all embodiments an endless track belt is employed with means automatically accumulating and paying out the exact running length of belt required according to the position of the various belt-engaging components.
Countless attempts have been made in the past to provide vehicles capable of negotiating irregular terrain and or possessing means faciliting maneuverability around or between obstacles and the present invention seeks to offer vastly improved means of an extremely compact nature yet possessing transport maneuverability not found in many known devices. With the present arrangement the vehicle undercarriage may readily negotiate narrow passageways and make relatively sharp turns while traversing supporting surfaces of even shiftable composition such as sand. In one selected mode, the instant vehicle may be adjusted to offer an extremely short wheelbase presenting contact with the supporting surface comprising only four transverse lines at the distal portions of the two spaced apart support assemblies while a simple manipulation achieves an appreciably extended wheelbase offering four relatively large foot-prints each presenting a substantially wide and long contact with the supporting surface.
Additionally, track belts having an improved construction are provided. By means of a central, longitudinally extending core each belt presents a medially localized contact surface or footprint with the underlying supporting surface thereby further enhancing the maneuverability of the apparatus. By employing either a solid or a semi or fully pneumatic belt core it will be appreciated that further adaptability is achieved to allow compatability with various types of supporting surfaces, whether they are smooth, rough, hard or shiftable.
Accordingly, one of the objects of the present invention is to provide an improved variable terrain vehicle having a motorized undercarriage including a pair of endless track drive mechanisms having means for altering the wheelbase thereof.
Another object of the present invention is to provide an improved variable terrain vehicle including track drive means having fixed-length endless tracks cooperating with means automatically vertically or horizontally taking up and letting out of slack in the belt during the alteration of the effective wheelbase of the vehicle.
Still another object of the present invention is to provide an improved variable terrain vehicle including track drive assemblies provided with pivotally displaceable subassemblies at their distal portions operable to extend/retract and/or vary the pitch of the fore and aft portions of the vehicle track.
Another object of the present invention is to provide an improved variable terrain vehicle including a pair of endless belt tracks supported about rollers variably positioned to offer either a line contact with the supporting surface therebeneath or a broad footprint having a substantial longitudinal and transverse extent.
Still another object of the present invention is to provide an improved variable terrain vehicle including an endless track drive provided with a flexible belt having a central, longitudinally extending core projecting beyond both surfaces of the track and which may be solid, semi-pneumatic or pneumatic.
Another object of the present invention is to provide an improved variable terrain vehicle including an endless track drive manually actuated by means of an occupant-controlled belt or chain mechanism.
With these and other objects in view which will more readily appear as the nature of the invention is better understood, the invention consists of the novel construction, combination and arrangement of parts hereinafter more fully described, illustrated and claimed.